COULD OF?? SHOULD OF?? WOULD OF??

Sometimes the casual expressions we use out loud creep into our written language in incorrect ways. Here is a good example of that from an article about a high school extemporaneous speech competition:

It was well said, and he probably could of gone on for another 6 minutes and 30 seconds.

When we say "could have" out loud, it SOUNDS like "could of," but it is not supposed to be written that way. OF is a preposition, but this phrase needs the helping verb HAVE to be correct. The sentence should read as follows:

It was well said, and he probably could have gone on for another 6 minutes and 30 seconds.

The 3,500 students who came to Birmingham last week for the United States Extemporaneous Speaking national competition at Oak Mountain High School were challenged to draw an unknown topic from a tray, spend 30 minutes researching it, and then prepare and memorize a seven-minute speech. Quite impressive.